Try 4-5 (or more) flicks and you also have to wait for the scrolling to happen (at the speed of your flick) .... contrast that with one "press" on iOS - it's not even close - I use the feature daily.
iOS devices aren't only used to browse source files or PDFs. You could be at the very bottom of an extremely long Reddit thread, for example, or some other really long page where it would take multiple swipes to get back to the top.
What's two flicks got that this doesn't? Or maybe if a shortcut was desired for extremely long views, why not make it a double tap?